Means for operating electric motors driving motor-trains.



w. A. T. MI I LLER.

MEANS FOR OPERATING ELECTRIC MOTORS DRIVING MOTOR TRAINS.

APPLICATION FILED MAEJ, 1911.

Patented May 16, 1911.

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w. A. T. MfiLLER.

MEANS FOR OPERATING ELECTRIC MOTORS DRIVING MOTOR TRAINS.

APPLICATION FILED M1111. 1,1911. 992,682, Patented May 16, 1911.

2 SHEETS-SHEBT 2.

. 5 6 b B 2 52, 2,11 ii: 14. p p 1 1 f U 'A L41 NrrNEss s lN\/ENTEJRWILHELM ADOLF THEODOR M'tl'IiLER, 0F BERLIN-STEGLITZ, GERMANY.

MEANS FOR OPERATING ELECTRIC MOTORS DRIVING MOTOR-TRAINS.

Specification of Letters Patent. Patented May 16, 1 911.

Application filed March 1, 191.1. Serial No. 611,715.

To all whom it may concern:

Be it known that LlviminnM Anon Tnnonon Mtinnnn, engineer, a subject ofthe German Emperor, residing at 5 Feldstrasse, Berlin-Steglitz, Germany,have invented certain new and useful Improvements in Means for OperatingElectric Motors Driving Motor-'lrains; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

This invention has for its object to provide improved means foroperating and controlling the electric motors of a motor train, in sucha manner that said motors may be run forward or backward, and electricbraking may be effected, from the car or vehicle of the driver, withoutthe necessity of providing cont-rolling switches on the other cars orvehicles of the train.

The invention consists substantially in supplying current from differentsources to the armature winding and the field winding of each electricmotor of the train, in the manner to be hereinafter described.

In the accompanying drawing, Figure l is a general side elevation of awagon train embodying the invention. which train is adapted to travel onordinary roads or highways, although the invention is obviously notlimited to this feature. Fig. 2 is a diagram of the motor controlsystemused inconnection with the above mentioned train, and Fig. 3 is adiagrammatic view of a modified system.

In the drawing M indicates the drivers vehicle of the train, which ispreferably arranged at the front, and which has coupled thereto a seriesof vehicles A A A.'". On the drivers vehicle is a dynamo l) having anarmature D and field D,- as shown in Figs. 2 and 3. This dynamo isdriven by meansof an internal combustion motor m or the like on'thedriversyehicle. by means of a suitable transmission not shown). and itis either self-excited or separately excited in such a manner that theelectric pressure can be varied in the ordinary way by means of acontroller G, the manipulation of which controls the speed of the trainfrom a standstill through very small increments up to the maximum. Theindidividual attached'vehicles'A A .A" are driven by means of electricmotors a, b;

of which any appropriate number may be used on each veh cle, and saidmotors comprise armatures a and field windings b, as shown in Figs. 2and 3. The armat-ures a are shown as connected in parallel by means ofleads or mains 1 and 2 which extend from the dynamo D throughout thelength of the 'train.- The field windings I) of theseveral motors areshown as being connected in series by means of leads or mains 3 and 4-which are quite separate from and independent of the main leads 1 and 2,and also extend through the train. The leads 3 and 4 are connected witha pole changing switch U tor'revcrsing purposes. and this switch'is inturn connected with a source of current separate from the main dynamoarmature.

In the arrangement shown in Fig. 2 the separate source of current forthe fields of the several motors is constituted by a storage battery B.which may be conveniently stored on the train. preferably on the driversvehicle. as shown. This battery, which is connected with the switch U inthe manner indicated, is adapted to be charged by the main dynamo D" andto be controlled by a suit-' able controller Z. With the arrangementdescribed there is no necessity for separate setting of the switch U foroperating the brakes, and also there is no necessity for providing aseparate resistance for destroying the braking energy. The current whichis generated in the armatures a of the electric motors in braking.passes directly into. the dynamo armature D. so that the latter runningas an electric motor drives its own driving motor (that is the internalcombustion motor m or the like). If desired the train can be braked bymerely throttling the supply of gas to the driving motor. In such a casethe driving motor is kept in motion hv the brake energy.notwiths'tandingthe said throttling. Consequently the brake energy isdestroyed by the consumption of energy due to the friction produced bythe to-and-fro motion of the motor pistonor pistons running idly. by thefriction of the crank shaft bearings. and by the back pressure due tothe compression in the motor cylinder or cylinders. The arrangementdescribed also has the additional advantage that a powerful brakingaction can be produced by means of the adjustable excitation of the.field windingsb afl'orded by the rheostat-controlled'storage batterycurrent, even when the train is stationary or moving at a very lowspeed, so that the train can be started on an incline with themechanical brakes in their off position. In the ordinary brakingsystems, the rotation of the motor armature is essential to theeneration of a.

braking current, as is well understood, but in the present instance, apowerful magnetic braking action may be exerted on the armatures so longas there is no current fiowlng throughthem, by suitably exciting thecorrespondingfield windings which therefore tend to prevent rotation ofthe armatures.

in the arrangement shown in Fig. 3, the current for the motor fields istaken from a separate and independent dynamo (i, f, which may beconveniently arranged in proximity to the main dynamo, although this isnot essential. The system difiers from that shown in Fig. 2 in so farthat the supply of current to the field windings is influencedautomatically by the main supply of current from the dynamo D" in such amanner that a determined ratio is established between the currentstrength in the electric motor armatures and the current strength in thefield magnets. This is important because, as is well known, the fieldmagnets of electric motors must not have too weak excitation relativelyto the armature currents. For this purpose, the field winding f, of thedynamo (Z, 7 for supplyi-n current to the motor fields, is composed o afew turns of coarse wire, so that the main current can be led directlythrough this field winding. The result of this is that the electricalpressure of the current of dynamo armature d is proportional to thecurrent supplied to the motor armatures, up to a certain degree, z'. e.,the point of approximate saturation of the field f; and the pressure ofsaid dynamo armature current w1ll become higher as additional vehiclesare coupled to the train, owing to the fact that increased current willbe sent through the motor armature circuit because of the increase inthe number of parallelconnected armatures. With the field windings 7)connected in series by means of the supply leads 3, 4, as shown, thestrength of the current in the field magnet windings can be keptconstant, notwithstanding an alteration in the number of the vehicles inthe train, because, as above noted, the pressure or tension suppliedfrom the dynamo armature d is proportional to the number of vehicles,and the resistance of the series-eonnected motor fields b is alsoproportional to the number of vehicles. As the tension and theresistance in the motor field circuit increase and decrease in the sameratio, the current must obviously remain constant. The" describedarrangement also has the effect that the fluctuations of current in thearmatures due to the variations in the resist ance of the road or track,will also occur in the field magnets in approximately the same degree asif each armature were connected in series with its own field. Thearrangement shown in Fig. 3 has in other respects the same advantages asthose possessed by the system shown in Fig. 2. For

the purpose of braking, however, it is necessary to reverse the switch Ubecause the braking current coming from the armatures a, has a reversedirection to the driving current, and consequently the current is alsoreversed in the armature d.

The series connection of the field magnet windings shown in theaccompanying drawings has the advantage over their parallel connection,that all the field magnets receive exactly equal exciting currents,sothat there is a great security that equal electro-motivc forces willbe produced in the armatures a. Any inequalities in the electro-motiveforces such as may be due to inequalities in the iron magnets of theseveral electric motors, can be compensated very accurately by means ofparallel resistances p which are included as required.

It is obvious that the invention is applicable to trains of varioustypes whether running on rails or on streets or roadways, and that Ihave not attempted to describe the various modifications which may beadopted without digressing from the invention.

I claim 1. In an electric motor train, a plurality of interconnectedvehicles, electric motors on a plurality of said vehicles, a pair ofmains extending through the train and permanently connecting in parallelthe armatures of the several motors, a second pair of mains alsoextending through the train and permanently connecting in series thefields of the several motors, a pole changing reversing switch connectedwith said last named mains, a source of current on the train connectedwith said reversing switch, a dynamo on the drivers vehicle connected tosaid first named mains and having exciting means associated therewith,the field of said dynamo being separate from and unaffected by thecurrent source of the motor field circuit, and a controller inconnection with said dynamo and by means of which the speed of the trainis regulated; substantially as described.

2. In an electric motor train, a plurality of connected vehicles, adynamo on one of said vehicles, motors on other vehicles and eachcomprising an armature and a field, mains permanently connecting saiddynamo with the armature windings of the several motors, and a separatesource of current connected with the field windings of the severalmotors and automaticall controlled by said dynamo to maintain preetermined relations said dynamo and between the currents in the circuitsof the motor armatures and fields respectively;

train from said dynamo and permanently connected to the several motorarmatures, separate mains extending through the tram and permanentlyconnected with the several .motor fields, a separate source of currentconnected with said last named mains and automatically controlled bysaid dynamo to maintain determined relations between the cur rents inthe motor armatures-and fields respectively, and controlling means forsaid dynamo whereby the speed of the train is regulated; substantiallyas described.

4. In an electricmotor train, a plurality of interconnected vehicles, adynamo on the drivers vehicle, means to operate said dynamo, acontroller associated with said dynamo, electric motors on othervehicles, mains extendin through the train "from connecting in parallelthe several motor armatures, said mains being permanently connected tosaid armatures, separate'mains extending through the train andconnecting inseries the fields of the several motor armatures, areversing'switch connected with said last named mains, and

dynamo; electric motors on other a separate source of current on thetrain, connected with said reversing switch and controlled from saiddynamo to maintain automatically determined relations between thecurrents in the armature and field circuits of the motors; substantiallyas described. g

'5. in an electric motorstrain, a plurality of interconnected vehicles,a dynamo on the drivers vehicle, means foroperatin said vhicles, andeach comprising an armature and a field-winding, mains extending throughthe train from said dynamo and permanently connecting in parallel thearmatures of the several motors, a controller associated with the dynamoby means of which the speed of the train is regulated, Imains extendingthrough the train and permanentlyconnect-f ing in series the fields ofthe several motors, a reversing switch connected with said last namedmains, and a second dynamo connected with said switch and having itsfield excited by the current flowing from saidv first named dynamo, soas to maintain automatically determined relations between the currentsin themotor armature and field circuits; substantially as describedl Intestimony whereof I have afiixed my signature, in presence of twowitnesses.

WILHELM ADOLF THEODOR MULLER- Witnesses:

HENRY HAsrER, WOLDEMAR HAUPT.

